This application relates to a device that is added into an interface between a gas turbine rotor and a transition duct to assist and guide the flow of purge air outwardly of an inner cavity.
A gas turbine engine, such as a turbo fan engine for an aircraft, includes a fan section, a compression section, a combustion section and a turbine section. An axis of the engine is centrally disposed within the engine and extends longitudinally through the sections. A primary flow path for working medium gases extends axially through the sections of the engine. A secondary flow path for working medium gases extends parallel to and radially outward of the primary flow path.
The fan section includes a rotor assembly and a stator assembly. The rotor assembly of the fan includes a rotor disk and plurality of radially extending fan blades. The fan blades span across through the flow path and interact with the working medium gases and transfer energy between the fan blades and working medium gases. The stator assembly includes a fan case, which circumscribes the rotor assembly in close proximity to the tips of the fan blades.
During operation, the fan draws the working medium gases, more particularly air, into the engine. The fan raises the pressure of the air drawn along the secondary flow path, thus producing useful thrust. The air drawn along the primary flow path into the compressor section is compressed. The compressed air is channeled to the combustion section where fuel is added to the compressed air and the air/fuel mixture is burned. The products of combustion are discharged to the turbine section. The turbine section extracts work from these products to power the fan and compressed air. Any energy from the products of combustion not needed to drive the fan and compressor contributes to useful thrust.
One challenge in the design of gas turbine engines, is that the hot gas in the area of the turbine can begin to move radially inwardly into an inner cavity. This would be undesirable. Ingestion of this hot gas can lead to corrosion of the components, which can lead to shortened part life. At one interface between the turbine rotor and an associated transition housing, purge air flow is directed radially outwardly from the inner cavity to resist this flow of hot gas. However, the present interface presents a tortuous flow path that makes it somewhat difficult to achieve an adequate flow of purge air. Due to this, undesirably large amounts of purge air are necessary. Utilizing large amounts of purge air can lead to lower component efficiencies, and higher thrust specific fuel consumption. This leads to higher fuel consumption for any given flight. Also, additional purge air that is utilized without being captured can result in higher combustion exit temperatures, and a potential reduction in turbine part life. It would be desirable to reduce the amount of purge air needed to resist the flow of hot gas.